In the related art, a battery module is mounted on an electric vehicle or the like. For example, JP-A-2012-256466 discloses a battery module which includes a cell stack, a pair of end plates disposed at both end portions of the cell stack in a stacking direction, and a pair of ladder frames connecting the pair of end plates.
In the battery module of this type, a load (hereinafter, referred to as cell thickness restraint reaction force as appropriate) in a cell stacking direction of the battery module is generated by cell expansion due to temperature change and aging deterioration. In recent years, due to an increase in cell capacity and an increase in energy density, it is in the direction of packing more active material in the cell, and thus the cell thickness restraint reaction force increases.
However, since a battery module of JP-A-2012-256466 includes a pair of end plates with high rigidity and receives cell thickness restraint reaction force at the pair of end plates, there is a concern in that the weight of the end plate and the battery module may increase significantly.